Barge carrying transport vessel

ABSTRACT

A vessel for transporting a plurality of barges is disclosed. A hull having a well deck adapted to support a plurality of barges has a plurality of ballast tanks adapted to be filled with sea water. When the ballast tanks are flooded, the hull is in a loading configuration, wherein the well deck is submerged so that barges can be floated over the well deck and positioned thereon. The ballast tanks, when empty, place the hull in a transporting configuration, wherein, the well deck is above water to transport the barges thereon. A wing wall is located on the edge of the well deck and is adapted to enclose the starboard side, the port side, and the bow thereof. The wing wall is adapted to be submerged when the hull is in the loading configuration and above water when the hull is in the transporting configuration.

i United States Patent [191 Cushing et al.

[ 1 BARGE CARRYING TRANSPORT VESSEL [75] Inventors: Charles R. Cushing, New York,

N.Y.; Stephen Phelps Henderson, Kentfield, Calif.; Paul Steven Wells, Mount Vernon, Wash.

[73]v Assignee: Inter-Hull, San Francisco, Calif.

22 Filed: Nov. 16, 1972 21 App]. No.: 307,291

[52] us. ca. 114/43.5. [51 rm. c1, B63b 35/28 [58] Field of Search 114143. 5, 72, 73, 56, .5 R, 1 14/5 A, 45, 47, 65 R, 26, 27; 9/31; 105/366 [56] References Cited UNITED STATES PATENTS 3,191,568 6/1965 Schroeder ll4/74- 3,403,652 10/1968 Hardy ll4/43.5 3,486,787 12/1969 Campbell 105/366 B 3,540,399 11/1970 Gabrielsson 114/72 3,587,505 6/1971 Wells ll4/43.5

FQREIGN PATENTS OR APPLICATIONS France 114/65 R in] 3,823,681 51 July 16," 1974 Primary ExaminerGeorge E. A. Halvosa Assistant Examiner'-Sherman D. Basinger Attorney, Agent, or Firm-Townsend and Townsend- [5 7 ABSTRACT A vessel for transporting a plurality of barges is disclosed. A hull having a well deck adapted to support a plurality of barges has a plurality of ballast tanks adapted to be filled with sea water. When the ballast tanks are flooded, the hull is in a loading configuration, wherein the well deck is submerged so that barges can be floated over the well deck and positioned thereon. The ballast tanks, when empty, place the hull in a transporting configuration, wherein, the well deckis-above water to transport the barges thereon. A wing wall is located on the edge of the well deck and is adapted to enclose the starboard side, the

port side, and the bow thereof. The wing wall is adaptedto be submerged when the hull is in the loading configuration and above water when the hull is in the transporting configuration.

9 Claims, 8, Drawing Figures PATENTEDJUH 6 I974 SHEU 1 91'' 5 PATENTEDJuu 6|974 I SHEU 3 0F 5 PATENTEB JUL 1 6 I974 SHEEI R [If 5 BARGE CARRYING TRANSPORT VESSEL BACKGROUND OF THE INVENTION This invention relates to seagoing vessels, and in particular to seagoing vessels adapted to transport a plurality of barges. The design of the vessel, including the method of placing the barges thereon, is disclosed.

Various designs of carrier vessels which are partially submergible have envolved. These vessels partially submerge so that barges containing cargo can be floated onto the carrier vessel. However, none of these designs have been commercially successful. and the only current vessels embodying this approach have small barges raised by gantries and loaded aboard the carrier vessel. This approach requires largeequipment to raise the barges, and is limited to relatively small barges.

All attempts to design a carrier vessel upon which barges could be loaded without lifting them out ofthe water have resulted in designs which, in one manner or another, were impractical. Many designs required the joining of independent parts to make up the total vessel, which is structurally impractical since the junctions cannot be made sufficiently strong to hold the vessel together in rough seas. Other designs, such as the patent to Wells,U.S. Pat. No. 3,556,036, provided no continuous structural connection along the sides'of the vessel, which results in a structurally impractical vessel design since fore and aft bending loads imposed on the vessel could not be conveniently counteracted. Further designs, such as the patentto Wells et al,, US. Pat.No. 3,587,505, provided enclosed inner chambers which are filled with water when the vessel is being loaded. However, the maintenance of a large enclosed chamber filled with water results in the establishment of dynamic motion of the water contained therein independent of the ambient seas. This destablizes the vessel to the point that it cannot be controlled; Still further designs have required complex gating arrangements to prevent influx of the water to the load-carrying decks while the vessel in underway. These gates were large and cumbersome, and limited the size of the opening which could be used to admit the barges.

SUMMARY OF THE INVENTION The invention relates to a vessel for transporting a plurality of barges including a hull having a well deck adapted to support the plurality of barges and further having a plurality of ballast tanks adapted to be filled with water to place the bull in a loading configuration. A wing wall is located on the edge of the well deck and is adapted to enclose the starboard side, the port side and the bow thereof, saidwing wall adapted to be submerged when the hull is in the loading configuration and above water when the hull is in the transporting configuration. A tower wall is provided on the wing wall and is adapted to remain above water when the hull is in the loading configuration.

OBJECTS AND ADVANTAGES OF THE INVENTION for the loading and unloading thereof.

An advantage of having the barges float over the well deck of the vessel is that the barges do not have to be lifted or raised in any manner during the loading and unloading thereof.

An advantage of not having to lift the barges during the loading and unloading thereof is that a small number of relatively largebarges may be used rather than a multiplicity of small barges.

A further advantage of allowing the barges to float onto the carrying vessel is that large, heavy equipment is not required to place the barges on the vessel.

An additional advantage of allowing the barges to float onto the carrying vessel is to reduce the superstructure of the vessel, since overhead cranes and gantries are not required to place the barges on the vessel.

A still further advantage of allowingthe barges to float on the well deck of the carrying vessel is that the barges may. be easily maneuvered to the position wherein they are to be secured by merely floating the barge into the proper position.

Another object of the invention is to provide a vessel for transporting a plurality of barges having a well deck for carrying the barges which is fully enclosed by a wing wall except at the stern. Entrance of the barges to the well deck is provided by the entrance at the stern of the vessel which is completely unobstructed by a wing wall or other structure. I

An advantage to having a well deck fully enclosed at the sides and the bow of the carrying vessel is that the surfaces of the vessel most exposed to the action of the sea are composed of an integral structure. An entrance opening at the side or bow of the carrying vessel would yielda weak point'in the construction of the vessel and would decrease the structural integrity of the vessel.

A further advantage to having the entrance for the barges at the stern of the carrying vessel is that the bow of the vessel provides protection for the stern entrance. Typically, a vessel pivots about its bow-mounted ground tackle when it is at anchor. The vessel disclosed herein is loaded while at anchor, at which time the bow is presented to the wind' and waves, and provides protection for the entrance at the stern.

An advantage of shielding the entrance from the wind and the waves is that the dynamic motion of the barge as it approaches the carrier vessel is minimized. A problem in the placing of a floating barge onto a floating carrying vessel is the synchronization of the dynamic motion of the barge with that of the carrying vessel at the entrance to the vessel. The'vessel, since it is far more massive and is more streamlined than the barge, is less subject to induced dynamic motion, and hence shielding the barge while allowing the vessel to be exposed to the ambient conditions results in relative synchronization of they dynamic motion of the barge with that of the vessel.

Yet another advantage of loading the barge at the stern of the vessel is that the barge is shielded from the wind and waves and is not subject to sudden gusts of wind or large waves as it approaches the entrance opening whereby it could suddenly be placed out of alignment with the entrance opening and ram the vessel. An advantage of minimizing the wave action on the barge as it approaches the entrance openingis that the pitching of the barge is minimized which reduces the clearance which must be allowed between the bottom of the barge and the well deck at the entrance opening.

An advantage of minimizing the ambient conditions in the well deck is that the pitching motion of the barge as it is being moved to its secured position in minimized, which decreases the clearance which must be provided between the bottom of the barge and the well deck. This in turn minimizes the total depth to which the hull mustbe submerged for placing of the barges thereon and simplifies the dynamic design of the hull configuration.

A still further advantage of loading the barges at the stern of the carrier vessel is that the barges are moved directly into the wind and waves as they are placed on the carrier vessel and secured, which allows for more accurate control and handling of the barges than would be possible if they were loaded either cross wind or down wind.

An object of the invention is to provide a carrier vessel having a single load' carrying well deck adapted to carry a single layer of barges, rather than several layers of decks adapted to carry several layers of barges.

An advantage of having a single layer of barges is that there were no communication with the sea, the motion of'the vessel in the ambient sea would cause a rolling and pitching motion of the water enclosed over the well deck. This motion could become highly unstable, and could rock the carrier vessel to the extent that the loading operation was not possible. Barges already on the vessel would move with the water over the well deck and impact the sides of the vessel, and the barges to be loaded could not be properly aligned with the entrance opening. The providing of communication with the sea prevents the buildup of such independent motion and enhances the stability of the vessel -while barges are relatively large vertical dimension barges may be accommodated. There is no restriction on the vertical dimension of the barges, as would be necessary if the positions, although adjustable ballasting can be provided to accommodate varying barge drafts.

A'further advantage of having a single layer of barges is that only a single load carrying well deck is required, and this load carrying well deck can be maintained above the water line during transportation of the barges.

An advantage of having the load carrying well deck above the water line when the carrier vessel is transporting the barges is that a watertight gate is not required to fully enclose the well deck as it would be if the well deck were below the water line.

A still further advantage of having the load carrying deck above water while the carrier vessel is transporting the barges is that the barges can be cleaned and reenclosing the starboard side, the port side and the bow of the well deck. This wing wall is above water when the carrier vessel is transporting the barges but is submerged when the vessel is in theprocess of loading or unloading the barges. During loading or unloading, the

wing wall provides communication between the water in the well deck and the ambient sea.

An advantage of providing communication between the water in the well deck and the ambient sea is that there is no buildup of dynamic motion of water in the well deck independent of the ambient sea condition. If i being placed thereon.

A further advantage of allowing communication of the water over the well deck with the sea is that an outlet is provided for the water in the well deck as barges are being placed thereon and an inlet is provided for water when barges are removed. In this manner, there is no rushing of water through the narrow spaces between the side of the barge and the walls on the ship to compensate for'movement of the barge. This effect would place the barge in a rapidly moving stream of water whichwould hinder the proper control of the barge and'would necessitate the design of undesirably large channels between the sides of the barge and the walls of the carrier vessel.

An advantage of providing submergible wing walls is that anentrance is supplied for water in addition to the entrance opening at the stern-of the vessel when the hull is being ballasted to place it in the configuration for loading barges. A corresponding exit forwater is provided when the hull is being deballas ted to place it in the configuration for transporting the barges.

A further advantage of the wing walls is that the wing walls are above water when the carrier vessel is deballasted and transporting the barges. A substantial amount of freeboard is provided along the sides of the carrier vessel when the carrier vessel is underway.

An object of the invention is to provide a plurality of I towerwalls located on top of the wing wall which surrounds the starboard side, the port side and the bow of the well deck. One tower wall is provided which completely encloses the bow portion of the vessel. Port and starboard tower walls are located amidship of the vessel and port and starboard tower walls are also located at the stern of the carrier vessel. Each tower wall comprises a watertight structural elevation.

An advantage of the bow tower wall is to provide additional freeboard at the bow of the vessel to facilitate movement of the carrier vessel through heavy seas.

. An advantage of having tower walls both in the bowand the stern of the vessel, and of having port and starboard tower walls at the stern of the vessel,.is to provide carrier v'essel stabilization during the loading and unloading thereof. The bow and aft tower walls provide longitudinal stability and reserve bouyancy, and the port and starboard aft tower walls provide athwartships stability and reserve buoyancy.

An advantage of having reserve buoyancy is to provide a safety factor in case of collision, leakage orother unanticipated problems.

An advantage of having port and starboard aft tower walls is to provide platforms or work islands for the loading of the barges over the stern of the vessel and ner of a loaded barge whereby the barges may be secured during the loading thereof while the wing walls are still submerged.

An object of the present invention is to provide a car rier vessel having no conventional weatherdeck over the barges. The barges are thus exposed to ambient conditions during the transportation thereof.

An advantage of not having a weather deck is the avoidance of a large cantilevered structure which adds needless weight to the carrier vessel.

A still further advantage of not having a conventional weather deck over the barges is that the center of gravity of the carrier vessel, either loaded or unloaded, is significantly lowered. This lowered center of gravity adds to the stability of the carrier vessel both when ballasted to place it in the loading configuration and when deballasted to place it in the transporting configuration.

A still further advantage of not having a weather deck enclosing the barges is that if a volatile, combustible cargo, such as natural gas, is carried in the barges, no enclosed area is provided for the possible dangerous buildup of such gases. Preventing the buildup of volatile gas .cargo in confined areas substantially increases the safety of the transporting operation and enlarges the potential scope of the cargo which can be carried.

A further object of the invention is to coordinate the design of the carrier vessel and the barges to be carried so that the barges substantially fill the well deck. In the design disclosed herein, the barges occupy in excess of 90 percent of the volume enclosed below the top of the wing walls in the well deck, and occupy approximately 85 percent ofthe area of the stern entrance through the wing walls.

An advantage of substantially filling the well deck by the barges is the provision of a highly efficient means of carrying the cargo wherein little volume of the carrier vessel is wasted.

' Another advantage of substantially filling the well deck is the reduction of the structural requirements of the carrier vessel. If the barges were spaced, increased moment loads would be placed on the carrier vessel in rough seasfand a stronger hull would have to be provided. I

An advantage of substantially filling the well deck with the barges is the minimization of the volume over the well deck which can be occupied by water. Such water can flow over the wing walls and in through the stern entrance when the carrier vessel is operating in rough seas.

An advantage of minimizing the amount of water which can collect over the well deck when the vessel is operating in rough seas is the prevention of destabilizing forces which can buildup if a large free surface of water is allowed to be maintained.

A still further advantage of substantially filling the well deck with the barges to minimize the potential accumulation of water thereon is to decrease the movement of water which could be a potentially serious problem when the hull is being raised from the loading configuration to the transporting transfiguration. The

problem is somewhat minimized by the submergible wing walls, but after the wing walls break water, the

only exit for the water over the well deck, other than I contained within the wing walls with the barges, and by interrupting the flow of the .water by the position of the barges, this problem is minimized.

A further advantage of substantially filling the well deck with the barges is the mutual confinement of all of the barges. If one barge breaks its mooring during rough seas,.it is still held in place by the other barges so that it is not allowed to accumulate momentum which could result in catastrophic damage to the carrier vessel itself.

An advantage of substantially filling 'the stern entrance to the well deck is the elimination of a requirement for a gate to close the entrance. Such'a gate would be extremely complex and hence costly, and would require the dedication of a substantial portion of the ship to the machinery involved in opening and closing the gate. A further disadvantage of the gate would be the location of a large mass at the extremity of the vessel, causing structural design problems. Another disadvantage of having a gate at the stern would be the elimination of the natural drainage provided by having a stern opening from the well deck The closure of the stern opening provided by the aft barge located in the opening and filling percent of that opening, together,

with the freeboard provided by the raised well deck, is sufficient to protect the vessel from following seas.

A still further object of the invention is to provide a carrier vessel having a well deck with slight positive camber. The need for excessive camber to provide high volume drainage is eliminated by the fact that the well deck is substantially filledwiththe barges to prevent a large accumulation of water.

An advantage of the slight camber is that the barge effectively bifurcates the well deck along the centerline of the well deck overlying the keel and divides the water accumulated on the deck into sections on each side of the barge whereby formation o fa large free surface of water is inhibited.

A further advantage of the cambered well deck is to provide drainage channels on each side of .the well deck.

An object of the invention is to provide a carrier vessel which can carry flat-bottom barges which are substantially similar'to barges in common use.

An advantage of using barges similar to those currently used is that the carrier vessel dimensions may be constructed about existing barges, eliminating the requirement for construction of new barges.

An object of the present invention is to provide a design of the foresection of the well deck and adjacent wing wallswhich can be tapered to conform to the bow shape of the barge. Barges are normally constructed with tapered foresections'of the hull to facilitate their movement through the water, and the carrier vessel disclosed herein is designed around the tapered foresection of the barge.

An advantage of conforming the foresection of the well deck and the wing walls to the taper of the barges is to minimize the'total length of the carrier vessel required to carry the same amount of cargo. Minimizing the length of the vesselminimizes the structural requirements and enhances the rigidity of the carrier vessel.

A further advantage of forming the foresection of the wall deck and the wing walls to the taper of the barges is the streamlining effect on the carrier vessel resulting in a more efficient hydrodynamic design of the carrier sel.

vessel. A still further advantage of forming the carrier vessel to a tapered barge design is to allow for the efficient hydrodynamic design of the barges themselves.

An object of the present invention is to provide a well deck which is tapered downward at the stern entrance to the well deck.

An advantage to tapering the well downward in the vicinity of the stern entrance opening is to allow for pitching of the barge as it is first being loaded and is not fully protected by the aft tower walls.

An object of the invention is to provide a carrier vessel which has a relatively high beam to draft ratio. greater than 4.6/1. which is substantially higher than that found in normal cargo vessels.

An advantage to providing a high beam to draft ratio is to provide a wide cargo area which allows for-the use of relatively large barges. Since only one layer of barges is accommodated in the present invention, the width of tion and while the vessel is in the transporting configuration.

An object of the invention is to provide the system of lines for loading and controlling'the position and attitude of thebarges. Two lines-are used to draw the barge onto the vessel. One drawing line runs from the starboard side of the bow of the barge to the starboard side of the vessel forward of the intended position of the barge. The other drawing line runs from the port side of the bow of the barge to the port side of the vessel. Two control lines are used to control the barge. One control line runs from the starboard side of the bow of the barge to the port side of the vessel aft of the intended secured position of the barge. The other control line runs from the port side of the bow of the barge to the starboard side of the vessel. The drawing line and the control line attached to the starboard side of the vessel form one set of crossed lines, and the drawing line and the control line attached to the port side of the vessel form a second set of crossed lines. Each pair of crossed lines is in spaced attachment to the bow of the barge and in spaced attachment to the side of the ves- An advantage of having two pairs of lines in spaced attachment to the bow of the barge to be loaded is to provide ready attachment of the lines to the barge without necessitating attachment of lines to the stem or other portion of the barge. Since the bow of the barge is nearest to the carrier vessel as the barge approaches the carrier vessel to be placed thereon, the lines can be easily transferred from the carrier vessel to their attachment location on the barge.

A further advantage to having two pairs of lines in A still further advantage of having two pairs of lines in spaced attachment to the bow of the barge to be loaded, with the lines crossed and having one of each pair of lines attached .to drawing means spaced relatively aft on the'carrier vessel is. that the aft lines wrap around the bow of the barge as it is being drawn onto the vessel and provide a means of controlling both the fore and aft movements of the barge as well as the lateral movement and attitude of the barge.

An object of-the invention is to provide push and pull rods tandemly mounted on the carrier vessel and engageable with corresponding cruciform fittings on each barge. The push and pull rods are engaged with the fittings on each barge after each barge has been drawn into the approximate secured position so that the barge may be exactly laterally positioned athwartships while the barge. is still floating.

An advantage of providing push and pull rods tandemly mounted on the carrier vessel is that the rods,

which are used to position the bargewhile it is still floating, can be maintained in engagement with the cruciform fittings on the barge as the vessel is raised to the transporting configuration, and serve to secure the barge during the transporting thereof.

An object of the invention is to provide tapered male pins extendable from the well deck and engageable with corresponding tapered female apertures on the underside of each barge.,The pins are extended after the barge has been positioned by the push and pull rods and while the barge is still floating. As the carrier vessel is raised to the transporting configuration, the barges settle down on the pins as the waterline drops, and are exactly positioned by the successive tapers of the pins with the corresponding female apertures. After the barge has settled on the well deck, the pins remain in engagement with the apertures to secure the position of the barge during the transporting thereof.

An advantage of having the tapered male pins engaged with the tapered female apertures is that the vessel is exactly centered in the transporting configuration. Thus, the vessel is loaded predictably on every occasion.

A further advantage of having the tapered male pins engage with the tapered female apertures is that the position of the barge is maintained during the transporting thereof without additional equipment to' secure the barge.

The novel features which are believed to be characteristic of the invention, both as to organization and method of operation,together with the further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawings in which a preferred embodiment of the. invention is illustrated by way of ex- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the vessel when empty.

FIG. 2 illustrates the vessel in the loading configuration, with a barge in the process of being loaded.

FIG. 3 illustrates the vessel in the fully loaded transporting configuration.

DESCRIPTION OF THE PREFERRED EMBOIDMENTS Referring to FIG. 1, the vessel is illustrated in the configuration for transporting barges but with the barges removed.'The vessel is composed basically of a hull 10 extending from the well deck 11 down to the keel (not visible). A wing wall 12 is located on the edge of the well deck 11 and fully encloses the well deck except at the stern of the vessel. Several tower walls are located on the wing wall 12. A forward tower wall 13 is located on the bow portion of the wing wall to pro vide a raised bow section. A pair of central tower walls 14 and 15 are located amidships, one central tower wall 14 on the port portion of the wing wall and one central tower wall 15 on the starboard portion of the wing wall. A pair of aft tower walls are located on the aft portion of the vessel, one aft tower wall 16 on the port portion of the wing wall and one aft tower wall. l7 on the starboard portion ofthe wing wall. A series of ports 19 provide access from the well deck 11 to the surrounding sea for the discharge of water from the well deck.

The embodiment illustrated in FIG. 1 is preferably adapted to transport barges carrying liquified natural gas, hence a vent stack 18 is provided at the stern ofthe vessel. The sole superstructure on the ship other than the bridge and living quarters 20 is located on the aft tower walls 16 and 17 and is used to support a control cab 21 suspended over the well deck 11. The superstructure is composed ofa catwalk 22 connected to the stacks 23 and 24 ofthe vessel. The use of stacks 23 and 24, which would be essential in any case, to support the control cab 21, plus the basic design of the ship results in an absolute minimum of superstructure. This lack of superstructure lowers the center of gravity of the vessel, and greatly simplifies the design of an efficient and stable hull configuration.

Since only a single load-carrying deck is used, the entire hull may be composed of ballast tanks. These ballast tanks are empty when the vessel is in the configura tion illustratedin FIG. 1, but can be filled with sea water to submerge the well deck 11 and place the vessel in the configuration for loading barges illustrated in FIG. 2. The ballast tanks in the hull are substantially filled with sea water so that the well deck 11 and wing wall 12 are submerged. and only the forward tower wall 13, central tower walls 14 and 15, and aft tower walls 16 and 17 are above water. The combination of wing wall and tower walls provide a multi-level structure which is partially above water and partially submerged when the hull is in the loading configuration. The well deck is sufficiently submerged so as to allow slight clearance between the well deck and the bottom of the floating barge 30.

The barge is pulled into position by means of lines 31 and 32 attached to the bow of the barge and connected to capstans 33 and 34 located forward of the intended secured position of the barge 30. The term capare crossed. Line 35 wraps around the bow of the barge, and together with line 31 and a corresponding pair of starboard lines provide control of the position and attitude of the barge 30 during the loading thereof. The pair of starboard lines consist of line 32 in combination with a hidden line attached to the bow of the barge on the starboard side thereof and connected to a hidden capstan on the aft starboard tower wall 17. To provide further control over the barge 30 as it passes through the aft entrance to the well deck-11, extendable rollers are provided on either side of-the entrance. The port extendable roller 37 is illustrated in the extended'position, with a similar starboard extendable roller hidden by the barge in the view shown. For added protection of the carrier vessel, rigid fenders 38 are provided which extendalong the interior of each wing wall l2 to prevent contact of the barge with the wing wall.

As a second and third barge are loaded on the vessel, successively aft capstans are used to draw the forward lines. Capstans 33 and 34 cannot be used since the first barge 30 would be in the way. Loading of .the aft barge 42 is illustrated by way of reference to FIGS. 6A, 6B,

and 6C. Lines 70 and 71 are attached to opposite sides of the bow of the barge 42, and run to capstans 72 and 73 on the starboard aft tower wall 17. As they are attached, as illustrated in FIG. 6A, the lines 70 and 71 are crossed. A corresponding pair of lines 74 and 75 are crossed and attached to capstans 76 and 77 on the port aft tower wall 16. v

As the barge 42 is drawn toward the vessel, (FIG. 6A), the two pairs of crossed lines provide attitude control over the barge. When the barge reaches the stern entrance to the well deck 11, extendable rollers 37 are engaged (FIG. 7). After the bow of the barge 42 passes the extendable rollers 37, the lines 71 and 75 attached to aft capstans 73 and 77 wrap around the bow of the barge as illustrated in FIG. 6C. In this position, the two sets of crossed lines provide foreand aft control of the barge as well as lateral and attitude control. The functions of the drawing lines and the control lines are reversed for unloading the barges. The loading operation can be supervised by personnel located in the suspended control cab 21, and the tower walls provide work platforms for the crew which can be used in the loading and securing of the barges.

Referring next to FIG. 3, the vessel is illustrated fully loaded in the transporting configuration. The well deck is above water, and is substantially filled with barges 30, 41 and 42. Although the three-barge configuration illustrated is preferred, the invention is equally applicable to configurations with different numbers of barges. The wing wall 12 is also above water, and in combination with the tower walls provide additional freeboard for the vessel when it is underway. In the embodiment illustrated, the volume enclosed by the well deck 11 and wing wall 12 is at least 90 percent filled by the barges. At the stern of the vessel, the aft barge 42 substantially fills the entrance opening, occupying approximately percent of the area thereof, which provides sufficient protection from following seas.

liquified natural gas, and a venting system must necessarily be supplied. The vessel illustrated has an integral venting system whereby the barges have vent pipes 43 attachable to corresponding pipes 44 on the port side of the carrier vessel. Pipes 44 are connected by internal pipes (not shown) to a vent stack 18 at the port side of the vessel. This system provides a unified means for venting excess natural gas vapor at the stern of the vessel (when permissible) in amanner calculated to minimize the dangers involved in transporting natural gas. Drain ports 19 also provide for drainage of liquified natural gas in case of accidental spills. 4

The means for accurately positioning and securing each barge in the transporting configuration is illustrated by way'of reference to FIG. 4. When the barge is still floating, as illustrated by dashed water line 51, and has been moved into the approximate transporting position, tandemly mounted push and pull rods 52 attached to an adjacent tower wall 53 are lowered to engage corresponding cruciform fittings 54 locatedon the barge. The push and pull rods are used to accurately position the barge 30 athwartships so that the center of gravity of the barge is aligned with that of the carrier vessel. After the barge has been positioned athwart ships, tapered male pins 55, which are disposed in the well deck 11, are raised to partially engage correspond-,

ing tapered female apertures 56 on the underside of the barge 30. The female aperture 56 has successive tapers as illustrated so that when the tapered male pin 55 is extended, the barge 30 is approximately fixed to its transporting position. ,As the hull 10 of the carrier vessel is deballasted so as to raise the well deck 11 above water to place the vessel in a transporting configuration as illustrated by water line 57, the barge 30 settles down onto the well deck 11 and the tapered male pin 55 is fully engaged with the corresponding female aperture 56 to exactly position and secure the barge in the transporting position as illustrated.

The conformation of the forward portion of the wing wall 12 andthe forward portion of the well deck 11 to the bow of the forward barge 30 is illustrated by way of reference to FIG. 5. The well deck 11 slopes upward as illustrated by inclined plane 61, and the wing wall 12 tapers inward as illustrated by the concave surface 62, to form a mutually tapered surface which conforms to the bow of the barge 30. This conformation streamlines the basic shape of the vessel, and minimizes the length of the vessel required to accommodate a given number of barges.

What is claimed is:

l. A vessel for transporting at least one or more cargo carrying barges comprising:

a-hull having a raised bow section for providing buoyant. forward support to said vessel at all drafts thereof;

a well deck mounted interiorly of said hull extending substantially horizontally parallel to the water lines of said hull, said well deck adapted to support on said hull said barges;

at least one ballast volume defined within said hull for permitting said hull to float at a first shallow draft, when said ballast volume is empty, said ballast volu'me when empty being of sufficient displacement with respect to said hull to maintain said well deck above the waterline of said vessel with said well deck fully loaded with cargo-carrying barges, and at a second deeper draft when said ballast volume is full of ballast, said well deck submerged at said second draft to provide for floating of the barges thereover to place said barges 5 thereon;

means for flooding and emptying said ballast volume of ballast;

a wing wall extending upwardly from said well deck at the bottom to a preselected elevation above said well deck, said wing wall extending from said how along the port side of said vessel, the starboard side ofsaid vessel, and defining acontinuously open u'nobstructed passage through the stern of said vessel for the entry and exit of cargo-carrying barges extending substantially the width of said well deck;

a portion of said preselected elevation ,of said wing wall deck selected to be below the water line of said vessel when said ballast volume is flooded to permit the entry and exit of water over said wing wall and above the water line of said vessel when said ballast volume is empty to retard entry and exit of water over said wing wall to said well deck;

at least one tower spaced aft of the bow of said vessel, said tower having a water-tight elevation adapted to provide buoyant support to said vessel remote from said bow at all drafts of said vessel between said first shallow draft and said second'deepe draft. I

2. The invention of claim 1 wherein the beam to draft ratio of said hull is approximately 4.6/1.

3. A vessel for transporting at least one or more cargo carrying barges comprising:

a hull having a raised bow section for providing buoyant forward support to said vessel at all drafts thereof;

a well deck mounted interiorly of said hull extending substantially horizontally parallelto the water line of said hull, said well deck adapted to support on said hull said barges during the transporting thereof;

at least one ballast volume defined within said hull for permitting said hull to float at a first shallow draft when said ballast volume is empty, said ballast volume when empty being of sufficientdisplacement with respect to said hull to maintain said well deck above the, water line of said vessel with said well deck fully loaded with cargo carrying barges,

' and at a second deeper draft when said ballast volume is full of ballast, said well deck submerged at said second draft to provide for floating of the plurality of barges thereover for the placing of said barges thereon;

means for flooding and emptying said ballast volume of ballast;

a wing wall located on the edge of the well deck and adapted to enclose the starboard and the port sides thereof, said wing wall adapted to be submerged when the hull is at the second deeper draft to pro vide communication of the sea thereover, and above water when the hull is at the first shallow draft, said wing wall defining a continuously open unobstructed passage through the stern of said vessel for the entry and exit of cargo carrying barges extending substantially the width of said well deck;

a pair of aft tower walls in the aft portion of the vessel, one aft tower wall on the starboard portion of the wing wall and one aft tower on the port portion of the wing wall, said aft tower walls having watertight elevations adapted to remain above water when the hull is at the second deeper draft to provide buoyant support at the aft portion of the vessel during the loading thereof.

4. A vessel as recited in claim 3 and additionally comprising a pair of central tower walls in the amidships portion of the vessel, one central tower wall on the starboard portion of the wing wall and one central tower wall on the port portion of the wing wall, said central tower walls having water-ti ght elevations adaptedto remain above water when the hull is at the second deeper draft.

5. A vessel as recited in claim 3 wherein the well deck is tapered downward at the stern thereof.

6. A vessel as recited in claim 3 wherein the well deck has a slight positive camber.

7. A vessel as recited in claim 3 wherein the forward portion of the well deck and the forward portion of the wing wall are tapered to conform to the bow shape of the forward barge.

8. A vessel as recited in claim 3 wherein the well deck is substantially flat and adapted to carry substantially flat bottom barges.

9. A system for transporting cargo by sea comprising:

draft when said ballast volume is empty, said ballast volume when empty being of sufficient displacement'with respect to said hull to maintain said well deck above the water line of said vessel with said well deck fully loaded with cargo carrying barges, and at a second deeper draft when said ballast volume is full of ballast, said well deck submerged at said second deeper sraft means for flooding and emptyingsaid ballast volume of ballast;

a wing wall located on the edge of the well deck and adapted to enclose the starboard and the port sides thereof, said wing wall defining a continuously open unobstructed passage through the stern of said vessel for the entry and exit of cargo carrying barges extending substantially the widthof said well deck, said wing wall adapted to be submerged when the hull is at the second deeper draft to provide communication of the sea thereoverand above water when the hull'is at the first shallow draft to inhibit entrance of water from the sea onto the well deck;

a plurality of barges adapted to float slightly above the well deck when the hull is at the second deeper draft whereby the barges may be floated over the stern of said well deck and secured over said well deck within the wing wall; I

at least one tower spaced aft of the bow of said vessel, said tower having a water-tight elevation adapted to provide buoyant support to said vessel remote from said how at all drafts of said vessel between said first shallow. drafts and said deeper draft. 

1. A vessel for transporting at least one or more cargo carrying barges comprising: a hull having a raised bow section for providing buoyant forward support to said vessel at all drafts thereof; a well deck mounted interiorly of said hull extending substantially horizontally parallel to the water lines of said hull, said well deck adapted to support on said hull said barges; at least one ballast volume defined within said hull for permitting said hull to float at a first shallow draft, when said ballast volume is empty, said ballast volume when empty being of sufficient displacement with respect to said hull to maintain said well deck above the water line of said vessel with said well deck fully loaded with cargo-carrying barges, and at a second deeper draft when said ballast volume is full of ballast, said well deck submerged at said second draft to provide for floating of the barges thereover to place said barges thereon; means for flooding and emptying said ballast volume of ballast; a wing wall extending upwardly from said well deck at the bottom to a preselected elevation above said well deck, said wing wall extending from said bow along the port side of said vessel, the starboard side of said vessel, and defining a continuously open unobstructed passage through the stern of said vessel for the entry and exit of cargo-carrying barges extending substantially the width of said well deck; a portion of said preselected elevation of said wing wall deck selected to be below the water line of said vessel when said ballast volume is flooded to permit the entry and exit of water over said wing wall and above the water line of said vessel when said ballast volume is empty to retard entry and exit of water over said wing wall to said well deck; at least one tower spaced aft of the bow of said vessel, said tower having a water-tight elevation adapted to provide buoyant support to said vessel remote from said bow at all drafts of said vessel between said first shallow draft and said second deeper draft.
 2. The invention of claim 1 wherein the beam to draft ratio of said hull is approximately 4.6/1.
 3. A vessel for transporting at least one or more cargo carrying barges comprising: a hull having a raised bow section for providing buoyant forward support to said vessel at all drafts thereof; a well deck mounted interiorly of said hull extending substantially horizontally parallel to the water line of said hull, said well deck adapted to support on said hull said barges during the transporting thereof; at least one ballast volume defined within said hull for permitting said hull to float at a first shallow draft when said ballast volume is empty, said ballast volume when empty being of sufficient displacement with respect to said hull to maintain said well deck above the water line of said vessel with said well deck fully loaded with cargo carrying barges, and at a second deeper draft when said ballast volume is full of ballast, said well deck submerged at said second draft to provide for floating of the plurality of barges thereover for the placing of said barges thereon; means for flooding and emptying said ballast volume of ballast; a wing wall located on the edge of the well deck and adapted to enclose the starboard and the port sides thereof, said wing wall adapted to be submerged when the hull is at the second deeper draft to provide communication of the sea thereover, and above water when the hull is at the first shallow draft, said wing wall defining a continuously open unobstructed passage through the stern of said vessel for the entry and exit of cargo carrying barges extending substantially the width of said well deck; a pair of aft tower walls in the aft portion of the vessel, one aft tower wall on the starboard portion of the wing wall and one aft tower on the port portion of the wing wall, said aft tower walls having water-tight elevations adapted to remain above water when the hull is at the second deeper draft to provide buoyant support at the aft portion of the vessel during the loading thereof.
 4. A vessel as recited in claim 3 and additionally comprising a pair of central tower walls in the amidships portion of the vessel, one central tower wall on the starboard portion of the wing wall and one central tower wall on the port portion of the wing wall, said central tower walls having water-tight elevations adapted to remain above water when the hull is at the second deeper draft.
 5. A vessel as recited in claim 3 wherein the well deck is tapered downward at the stern thereof.
 6. A vessel as recited in claim 3 wherein the well deck has a slight positive camber.
 7. A vessel as recited in claim 3 wherein the forward portion of the well deck and the forward portion of the wing wall are tapered to conform to the bow shape of the forward barge.
 8. A vessel as recited in claim 3 wherein the well deck is substantially flat and adapted to carry substantially flat bottom barges.
 9. A system for transporting cargo by sea comprising: a hull having a raised bow portion for providing buoyant forward support to said vessel at all drafts of said vessel; a well deck mounted interiorly of said hull extending substantially horizontally parallel to the water lines of said hull; at least one ballast volume defined within said hull for permitting said hull to float at a first shallow draft when said ballast volume is empty, said ballast volume when empty being of sufficient displacement with respect to said hull to maintain said well deck above the water line of said vessel with said well deck fully loaded with cargo carrying barges, and at a second deeper draft when said ballast volume is full of ballast, said well deck submerged at said second deeper sraft means for flooding and emptying said ballast volume of ballast; a Wing wall located on the edge of the well deck and adapted to enclose the starboard and the port sides thereof, said wing wall defining a continuously open unobstructed passage through the stern of said vessel for the entry and exit of cargo carrying barges extending substantially the width of said well deck, said wing wall adapted to be submerged when the hull is at the second deeper draft to provide communication of the sea thereover and above water when the hull is at the first shallow draft to inhibit entrance of water from the sea onto the well deck; a plurality of barges adapted to float slightly above the well deck when the hull is at the second deeper draft whereby the barges may be floated over the stern of said well deck and secured over said well deck within the wing wall; at least one tower spaced aft of the bow of said vessel, said tower having a water-tight elevation adapted to provide buoyant support to said vessel remote from said bow at all drafts of said vessel between said first shallow drafts and said deeper draft. 